[Pgpool-general] Using pgpool-II with PostgreSQL 8.3 and 9.0 at the same time

[Karl Lehenbauer]

Hi,

We have slony replication running with a 4 node cluster and we have been using pgpool-II for a long time, to load balance certain queries.  

Now we are preparing to migrate to PostgreSQL 9.0.  Currently, one of our slony slaves is running 9.0 and all the other nodes (master and slaves) are running 8.3.

We would like to use pgpool to connect to the 8.3 and 9.0 servers at the same time -- our systems are pretty busy and we would like to stay up with three nodes as we migrate them one-by-one to 9.0.

When we try to connect pgpool-II to 8.3 and 9.0 Postgres versions at the same time, the connection startup code gets out of sync... pool_do_auth calls ParameterStatus, and ParameterStatus gets out of sync because the 9.0 server sends "application_name" and the 8.3 servers do not.  (I saw a recent commit to support application_name but I realize it was not designed to address this issue.)

So my question is... is it possible to run pgpool-II with 8.3 and 9.0 at the same time, or should we just work out a way to switch pgpool all at once from 8.3 to 9.0?

Thank you for pgpool-II !

Karl Lehenbauer
FlightAware.com

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